Light-sensitive materials



Patented Nov. 26, 1948 r 2,411,811 ucn'r-sansmva mraams General Aniline York, N. Y.,

Donald Edward Sargznt,

Easton, Pa., asslgnorto Film Corporation, New a corporation of Delaware No Drawing." Application February 1, 1945, Serial No. 515,131

This invention relates to photoprinting material for the direct reproduction oi positive prints from positive originals and negative prints from negative originals. More particularly, it relates to a photoprinting material comprising a light sensitive element which will decompose upon exfurnish a dye component in posure to light and to the process of its undecomposed form and producing such photoprinting material.

Many processes have been suggested for the I production of photoprinting material of this type,

such processes differing principally in the chemical used as the light sensitive element and in the manner of developing a dye image. The most widely known of these processes are those which are based upori the light sensitivity of aromatic diazo compounds. Other such processes of less importance include processes based upon the light sensitivity of the leuco compounds of the coal tar dyestuffs; processes based upon the oxidizing action of o-nitro groups in aromatic systems having aliphatic side chains, as for instance o-nitrophenyl lactic acid methylketone; and processes based upon the light sensitivity of the o-nitrodiaminotriphenyl-methane bases. exception of the processesbased upon the light sensitivity of aromatic diazo compounds, these suggested photoprinting processes for the reproduction of positive copies from positive originals have found no commercial adaptability either because of the instability of the compounds employedor the diiilculty of developing the dye image from the undecomposed light sensitive material. The aromatic diazo compounds have found wide commercial acceptance in two wellknown processes which are designated respectively as the one-component or wet-development process and the two-component or dry-development process. In the one-component process, the aromatic diazo compound is incorporated into a light sensitive layer on the carrier which may be paper, foil, glass or a metallic surface, and after exposure under the original to be copied is developed by contact with a solution of the coupling component necessary to produce the ultimately desired image, In the two-component process, the aromatic diazo compound and the coupling component necessary to produce the dye image are both incorporated in the light sensitive layer on the carrier. In this case, the development of the dye'image is effected after exposure by contacting the light sensitive layer with ammonia gas. For optimum results, it is necessary to limit the selection of the diazo compound to the diazo compounds derived from aromatic p-diamines and o-aminonaphthols since premature coupling of the dye components takes place if other types of diazos are used in the light sensitive layer together with the coupling compo- With the 1 8 Claims. (Cl. 95.6)

nent, thus reducing the keeping quality of the coated carrier..

In photoprinting processes of this type, it is highly desirable to produce a copy which will have a clear white background and which will not .be subject to discoloration in the background due to aging. It is also desirable to have a material which will give gradation ofshade throughout the high light and half tone areas. In the case of the aromatic diazo compounds, the light decomposition products remaining in the background will become discolored after a short time and in view of this characteristic it has been found necessary to incorporate materials which will partially inhibit or retard this tendency toward discoloration in order to maintain a reasonably acceptable clear background.

It has now been discovered that another class of compounds may be used as the light sensitive element in the preparation of positive reproduction photoprinting materal which, when coated onto a suitable carrier such as the paper, foil, glass or metallic surfaces mentioned above, together with a suitable dye component will form an azo dye when developed in a proper medium and will decompose to a non-dye forming compound upon exposure to light. This class of compounds may be designated as N-nitroso-N- arylamides. These nitrosoarylamides are stable in neutral and weakly acidic media but are sensitive to both alkalie and strong acids. They may be represented by the following general formula (Ar) III-N 0 v Ac :1

or derivatives of such structures; Ac is an acylgroup or group having similar characteristics such as --COR, CONR2, -,C(=NR) NR2, -CN,

COOR, -SO1R, -SO2NR2, COCOOR, -SO3M+, -COO-M+, -CSNR:, R being an alkyl, aralkyl or aryl group or a hydrogen atom, and M+ being a metallic or metalloid cation; and n is an integer from 1-3.

As is well known, these nitrosoamides when reacted with an alkaline compound will rearrange to a form which will combine with an azo coupling component to form an azo dye. This molecular rearrangement which is thus induced takes 7 place in two steps involving ashift in the acyl group to the nitroso group and hydrolysis to give an aryl diazotate salt in accordance with the.

following reactions:

It is this hydrolysis product or aryl diazotate salt which is utilized to produce the azo dye image by coupling with an azo coupling component and hence the treatment of an.N nitroso- N-arylamide with an alkali in the presence of an azo coupling component will produce a dye. These N-nitroso-N-arylamides are also altered by treatment with a strong acid such as hydrochloric acid, the end product in that case being a diazonium salt. Specifically, it is presumed to follow the following reactions:

HX EX ArN-NO ArN=NO C R ArN=NOH+HO C 0 R o R H10 (X-anion of strong acid) As is indicated above, a light sensitive material to be suitable for positive photoprinting purposes in a practical sense must be capable of forming a dye image upon development with another dye component and in the case of twocomponent layers, the light sensitive material must be such that it will not readily couple with the other dye component in the absence of the coupling medium. Preferably it should be incapable of coupling in the absence of a coupling medium. In addition, the light sensitive material must be decomposable to a compound which will no longer perform the dye function. This is necessary in order to insure the absence of color in the high light areas or in the areas which are exposed to light by reason of the absence of lines or figures in the original which otherwise would prevent the passage of light through the original. The N-nitroso-N-arylamides of this invention, as indicated in the above equations, will couple with an azo coupling component to form a dye in the presence of an alkaline medium. They are stable and will not couple with an azo coupling component in the absence of an alkali. As indicated above, the N-nitroso-N- arylamides are altered to diazonium salts by strong acids. However, they are not changed by weak acids and are particularly stable in solution having a pH of from about 5 to 7. Furthermore, it has now been found that they are sufficiently light sensitive to form the basis of a positive photoprinting material and that upon exposure to light they will decompose to products which will no longer couple to form a dye. It has also been found that the light decomposition products of the N-nitroso-N-arylamides do not readily couple with residual undecomposed N- nitroso-N-arylamide compounds and do not otherwise contribute to the formation of discoloration in the exposed areas of the reproduction. Thus, the white areas of the reproduction remain white for long periods of time and do not become discolored except by possible aging of the paper or other carrier employed in the productionof the photoprinting material.

In its preferred embodiment, the process of this invention is carried out by coating a suitable base such as paper a cellulose or cellulose ester film, glass plate, textile material, gelatinized surface or metallic surface with a coating preparation containing an N-nitroso-N-arylamide compound, an azo coupling component such as a phenolic substance or a compound having an active methylene group, a mild acid such as citric 7o or acetic acid and water. The coating is effected inthe usual manner by applying the coating solution to the surface of, the carrier or base material with a doctor blade or by spraying.

The coated material is then dried, exposed under 75 i vents of high volatility, such'as alcohols, ethers,

and ketones, as for example, acetone, may be employed in place 01' water. Such diluents may be employed'to makeup the nitrcsoamide and coupler coating solution in cases where the base material or carrier is such that it ill resist the penetrating and solvent action of the diluent. High temperature drying may thus be avoided.

In another manner of carrying out this process only the N-nitroso-N-arylamide compoi-s'd is added to the mild acid solution and coated onto the carrier. The exposure under a suitable positive is effected as before but the image is developed by bathing the exposed element in an alkaline bath containing the azo dye coupler necessary to combine with the undecomposed nitrosoamide compound to form a dye in the unexposed areas. In this modification of the process, it is desirable, although not necessary, to employ a 'non-migratory"'N-nitroso-N-arylamide such as CeH5N(CONHCicH7) NO Here the self-coupling nitrosoamide is added to mildly acid aqueous solution and coated onto a suitable carrier in the usual manner. It is then exposed to a suitable source of light under a positive and developed by merely contacting the unexposed areas with ammonia vapor or a solution of an alkaline compound. This alkaline developing treatment produces the necessary rearrangement in the nitrosoamide molecule to produce the chromophore group and at the same time effects the coupling of the thus rearranged molecule with a degradation product of the nitrosoamide compound. It is believed that the nitrosoamide after rearrangement couples with the naphthyl amine fragment resulting from rearrangement hydrolysis, and decarboxylation which is presumed to take place in accordance with the following scheme:

'NP NHiOH I o Qmnoocnntl) I m ON=N-ONH4 NHlO 0 CNH nmoocmrm 11mm +NH,+co,,

ina, v y: @nvnamo in the specific oped to a brownish orange. color. I

Although it'is not essential, it is understood that, if desired, auxiliary materials may be added to the coating solution in any of tile process which'materials may function as stabilizers. preservatives, extenders, color intensiiirs, and light sensitive intensiflers. A wide range of colors may be produced by this process. By proper selection of the coupling component the N-nitroso-N-arylamide light sensitive layers can be made to reproduce the image in almost any desired color. Suitable coupling components for this purpose include resorcylic acid, phenol, resorcinol, chromotrope acid, 2,3- dihydroxynaphthalene, H-acid, R-salt, 2-hydroxy-l-benzene-sulfonic acid, 2,5-dimethyl-6-udimethyl aminomethyl-l-phenol, the aminoethylamide of 2,3-hydroxynaphthoic acid, phloroglucin, 2,3 dihydroxy naphthalene monooxyethylether, and B-naphthol-iifi-disulfonic acid.

The N-nitroso-N-arylamides of this invention are most sensitive to light waves in the violet and ultraviolet range. Consequently, any source of light such as a quartz mercury vapor arc lamp which emits rays in that region may be employed for exposing the light sensitive layer for the purpose of decomposing the N-nitroso-N-arylamide in the high light areas. Other sources of light which may be employed include incandescent lamps, are lamps, and fluorescent lamps. However, the process is not necessarily restricted to the frequencies of the violet and near ultraviolet range since the sensitivity of the'nitrosoamides could be adjusted to permit the absorption of other frequencies such as those in the red and blue ranges.

The practice of this invention may be best understood by reference to the following specific examples which are presented as illustrative of the process involved and without any intention of introducing limitations. Unless otherwise stated, the partsgiven are by weight.

Example 1 A solution was made up containing parts of p-methoxy-phenylurea, and 50 parts of glacial acetic acid.

This solution was treated with a concentrated of the modifications instance of the N-nitroso-Ne phenyl-N' p-naphthyl-urea, the image is devel solution of sodium nitrite until nitrosation was complete.

The N-nitroso-N- (p-diethylaminophenyl) -urea obtained from this nitrosation was added to a solution containing 10 parts of resorcylicacid and 50 parts of. water.

positiv image having a clear white background.

In this example if the 10 parts of resorcylic acid be replaced by 10 parts of phenol, the original will be reproduced in a yellow dye image. The

. time of exposure may be reduced considerably by substituting a lamp of higher efliciency, such as a "G. E. 360 BL lamp for the 100 w. lamp.

Example 3 A solution containing 5 parts of p-phenylenediurea in parts of glacial acetic acid was treated with one equivalent of sodium nitrite (about 1.7 parts) dissolved in a small amount of water. The resulting solution of nitrosoamide was added to a solution containing 10 parts of H-acid (8- amino-l-naphthol-3.6-disu1fonic acid) in 500 parts of water. I

The resulting mixture was coated onto a paper strip and allowed to dry in the dark. It was then exposed to light under a positive transparency and the exposed coated paper developed by contacting same with ammonia vapor. The design of the positive transparency was developed to a purple positive dye image on a clear white background.

Example 4 A solution containing 5 parts of N-nitroso-N- aqueous solution of sodium nitrite until nitrosation was complete.

The resulting solution of N-nitroso-N-(pmethoxyphenyl) -urea was then added while stirring to a solution containing 10 parts of chromotrope acid (1.8 dihydroxynaphthalene 3.6-disulfonic acid) in 500 parts of water.

This mixture was coated onto a paper strip and dried. The coated paper strip was then exposed under a positive to the light from a quartz mercury vapor arc lamp. The positive original was removed and the exposed coated paper developed by inserting it in a chamber filled with ammonia fumes. The image on the original was developed as a positive magenta colored print having a clear white background. In this example, if the 10 parts of chromotrope acid be replaced by 10 parts of 2.3-dihydroxynaphtbalene the original will be reproduced in a dark blue image.

Example 2 A solution containing 5 parts of p-diethylaminophenyl-urea acid was treated with a concentrated aqueous and 50 parts of glacial acetic invention, and having to perform it, what I 2-phenyl-4-p-naphthylsemicarbazide and 50 parts of glacial acetic acid was added to 500 parts of water and the resulting mixture coated on strips of paper, cloth, and gelatinized glass plates and dried in the dark.

The dried coated strips of paper, cloth, and gelatinized glass were each exposed to light under a positive transparency and the thus exposed elements developed by contracting same with ammonia gas, the images in each case were developed to a brownish orange color on a clear background.

' Example 5 An acetic acid solution of N-nitroso-N-phenylstearamide prepared by nitrosation of N-phenylstearamide with nitrous fumes in glacial acetic acid was coated onto a textile base and allowed to dry in the dark. The dried coated textile was then exposed to a proper source of light under a stencil. It was then placed in a solution containing 10 parts of R-salt (2-naphthol-3.6-disulfonic acid) and 20 parts of sodium carbonate in 500 parts of water.

It was then washed and dried. A very excellent printed textile was thus obtained having the design of the stencil reproduced in a bright red color on a clear background.

Having now set forth and fully described my illustrated the best manner desire to protect by Letters Patent and, therefore, claim is:

l. The process of producing a photoprinting material which comprises coating a solution oi a 7 light-sensitive N-nitroso-N-arylamide onto a suitable carrier and drying.

2. The process of producing a photoprinting material which comprises coating a solution com: prising a light-sensitive N-nitroso-N-arylamide and an azo coupling component onto a suitable carrier and drying.

3. The process of producing a photoprinting material which comprises incorporating a lightsensitive N-nitroso-N-arylamide and an azo coupling component into a weakly acid aqueous solution, coating the resulting solution onto a suitable carrier and drying.

4. The process of producing a photoprinting material which comprises incorporating N-nitroso-N-Kp-diethylaminophenyl) -urea and an azo coupling component into a weakly acid aqueous solution. coating the resulting solution onto a suitable carrier and drying.

5. The process of producing a photoprinting material which comprises incorporating N- nitroso-N-phenylstearamide and an azo coupling component into a weakly acid aqueous solution, coating th resulting solution onto a. suitable carrier and drying.

6. The process of producing a photoprinting material which comprises coating a solution N-nitroso-N-phenyl-N'-p-naphthylurea in weak acetic acid onto a suitable carrier and drying.

7. Photoprinting materials comprising as-the light sensitive element a light-sensitive N-nitroso-N-arylamide compound.

8. Photoprinting materials comprising in combination a light-sensitive N-nitroso-N-arylamide compound as the light sensitive element and an azo coupling component.

9. Photoprinting materials comprising a light sensitive layer on a suitable carrier, said light sensitive layer containing a light-sensitive N- nitroso-N-arylamide as the light sensitive element.

10. Photoprinting materials comprising a light sensitive layer on a suitable carrier, said light sensitive layer containing an N-nitros'o-N-arylamide as the light sensitive element and an azo coupling component.

11. Photoprinting materials comprising a light sensitive layer on a suitable carrier, said light sensitive layer containing N-nitroso-N-(p-diethylaminophenyD-urea as the light sensitive element and an azo coupling component.

12. Photoprinting materials comprising a light sensitive layer on a suitable carrier, said light sensitive layer containing N-nitroso-N-phenylstearamide as the light sensitive element and an azo coupling component.

13. Photoprinting materials comprising a light sensitiv layer on a suitable carrier, said light sensitive layer containing N-nltroso N-phenyl- N'-,8-naphthylurea as the light sensitive element.

tacting it with a developing agent selected from the group consisting of alkalis and strong acids in the presence of an azo dye coupling component.

15. The process of reproducing an original in its photographically positive image which comprises placing the original under a photoprinting material consisting of a carrier having alight sensitive layer which contains as the light sensitive element a light-sensitive N-nitroso-N-arylamide and an azo dye coupling component, exposing the photoprinting material to light through the original and developing the image of the original of the photoprinting material by contacting it with ammonia fumes.

16. The process of reproducing an original in its photograph'ically positive image which comprises placing the original under a photoprinting material consisting of a carrier having a light sensitive layer containing N-nitroso-N-(p-diethylaminophenyD-urea as the light sensitive element and an azo dye coupling component, exposing the photoprinting material to light through the original, and developing the image of the original on the photoprinting material by contacting it with ammonia fumes.

17. The process of reproducing .an original in its photographically positive image which comprises placing the original under a photoprinting material consisting of a carrier having a light sensitive layer containing N-nitroso-N-phenyl stearamide as the light sensitive element, exposing the photo-printing material to light through the original, and developing the image of the original on the photoprinting material by treating it with an alkaline solution of an azo dye coupling component.

18. The process of reproducing an original in its photographically positive image which comprises placing the original under a photoprinting material consisting of a carrier having a light sensitive layer containing N-nitroso-N-phenyl- N -,s-naphthylurea as the light sensitive element, exposing the photoprinting material to light through the original, and developing the image of the original on the photoprinting material by contacting it with ammonia fumes.

DONALD EDWARD SARGENT. 

